Stable aminoplast cellular foams and the process for their manufacture

ABSTRACT

Stable, emission-free, low-shrinkage, fireproof aminoplastic cellular foams are obtained by using an unsaturated, halogenated polyalcohol in the resin precondensate constituent and a dodecylbenzolsulphonic acid partially esterified preferably with a fatty alcohol and a long-chain polyhydric alcohol, preferably a polyethylene glycol, in the foaming agent hardener consituent. The foams are particularly suitable for building construction and for covering, as well as in the agricultural sector and or oil absorption. For certain of these applications, the resin pre-condensate constituent of the invention can be processed with a conventional foamer hardener constituent or the foamer hardener constituent of the invention can be processed with a conventional resin precondensate constituent.

The invention relates to stable, shrinkage-free, possibly fireproofand/or emission-free aminoplastic cellular foams and the process formanufacturing them from carbamide-formaldehyde resin condensate(subsequently referred to as "amino resin precondensate") and a hardenerfoaming agent as well as amino resin precondensate constituents andhardener foaming agent constituents for manufacturing such foams.

Aminoplastic resin cellular foams have been in use for decades. However,the use of these cellular foams as, for example, filling material forhollow space in building construction, has been limited thus far due totheir instability, heavy shrinkage and undesirable emission offormaldehyde. This is primarily because it has not been possible totransfer the laboratory results achieved thus far to the work site (see,for example, DIN 18159, Part 2, where 4% shrinkage is tolerated). Inaddition, the conditions for shrinkage, related to the release offormaldehyde, have been unsatisfactorily resolved. Therefore in recentyears aminoplastic cellular foams in building construction have beenalmost totally driven from the market.

As of today polyhydric alcohols, such as, for example, polyethyleneglycol, diethylene glycol, sorbitol, etc. are state of the art additivesto the resin precondensate solution (see, for example, DE-PS 1.054.232,U.S. Pat. No. 2,542,471). The use of these, presumably molecule chainstabilizing alcohols, is limited by the constituent amounts. A surplusof alcohols reduces the fireproof capability of the foams. In order tomaintain this fireproof capability nevertheless, ortho-boric acidtransformation products, for example, were added to alcohol surpluses asa counter measure.

By adding boric acid esters it was possible to improve the resin qualityor cellular foam quality, but the products were still not completelysatisfactory (DE-PS 2.542.471).

Also proposed as formaldehyde binding for the manufacture oflow-formaldehyde products is the introduction into the foaming agent ofcarbamide in concentrated form (DE-PS 32 16 897). Resorcinol is alsoused for this purpose in the conventional foaming agent solutions. Inaddition, phosphoric acid is used as a resin (DE-PS 32 16 897).

One object of the invention under consideration is the creation ofaminoplastic cellular foams with optimal stability with large volume andlow weight. An additional task of the invention under consideration isthe creation of low-shrinkage and/or emission-free aminoplastic cellularfoams.

The term "stable" refers, in relation to the invention underconsideration, to the foam's ability to resist decomposition.

The term "low-shrinkage" means in this case a linear shrinkage, at woodindustry standard conditions, of less than 4%, preferably of less than1% and generally preferred of, at the most, 0,2%.

By "emission-free" the understanding here is of foams that exhibit nodetectable smell of formaldehyde during and after hardening.

These objects will be accomplished in accordance with the invention bythe composition of the foaming agent hardener constituent on the onehand, and/or the resin precondensate constituents on the other. Theaminoplastic cellular foams according to the invention and the processfor manufacturing them as well as the foaming agent hardenerconstituents and resin precondensate constituents for manufacturing suchfoams are defined in the independent claims. Preferred embodiment foamsare to be found in the dependent claims.

For the manufacture of emission-free, low-shrinkage, fireproofaminoplastic cellular foams used for the most part as sound and heatinsulation in building construction, although for other purposes aswell, a halogen--(preferably bromide)--alkylene-polyol, for example1,4-dibromide-2-butene-1,4-diol, is added to the resin precondensatesolution along with common polyhydric alcohols. The alkylene group ofthese polyols includes unsaturated olefine groups with one or moredouble bonds. Although the reaction mechanism has not been completelyexplained, it is assumed that these compounds bind with the availablefree formaldehyde as well as with the available methylol groups, thatcan convert to formaldehyde, and produce stable compounds at both highand low temperatures environments.

Along with the foam's low level of inflammability (corresponding to thespecifications of Swiss Fire Class V/3) brought about by the halogencompound, aminoplastic cellular foams of historically unknown stabilitycan be achieved with this additive. Proteolytic reactions as a result ofexternal physical influences on the final hardened foam are completelyeliminated under normal conditions.

The products suitable as aminoplastic precondensate solutions are thosemanufactured by conventional means, and obtained by conversion fromcarbamide and formaldehyde in a mol-relation 1:1.25 to 1:2.5, preferred1:2, at about pH 4 to 6 in about 30 to 70% water solution. Resinprecondensates obtained with a content of approximately 30 to 40percentage by weight solids are preferable. These kinds of products canbe obtained commercially or easily manufactured by conventional means.

These resin precondensate constituents extended with additives inaccordance with the invention can be converted in a conventional mannerwith a known, commercial foaming agent hardener constituent, or with thefoaming agent hardener constituent, according to the invention anddescribed below, and conventionally processed to a foam.

When, on the other hand, fire resistance does not play a large role andshrinkage is unimportant, as, for example, when using the foaming agentfor covering or for oil absorption, commercial carbamides formaldehydeprecondensates can be converted with the foaming agent hardeners thatare in accordance with the invention.

It is, however, desirable or necessary to keep the shrinkage duringhardening to a minimum, as is the case, for example, in buildingconstruction, and surprisingly it was discovered that completelyunexpected results are achieved when using a foaming agent solutionbased on dodecylbenzolsulphonic acid, which, if necessary, is partiallyesterified with one or more fatty alcohols, for example, a polyethyleneglycol. In this case molecule chain stabilizing and therefore shrinkagereducing effects were recorded. A better surface distribution of thewater and an optimal foam cell structure with simultaneous omission offoam volume loss occurred. The intensity of the foam can be optimallycontrolled as desired by the degree of the esterification of thesulfonic acid. Fatty alcohols with 15 to 22 carbon atoms are mostsuitable for esterification.

Many inorganic and organic acids, as they are known among specialists,make for suitable hardeners. It is best to use 85%, hydrous phosphoricacid requiring only a portion of the former standard amounts. Theinorganic acid portion for hardening consists only 1/4 to 1/3 of theestablished amounts necessary for the hardening of aminoplastic resinuntil now. The surface tension of the foaming agent can be selectivelyinfluenced by the amount of applied polyethylene glycol.

Polyethylene glycol is an additional factor in the construction of thefoam structure and acts simultaneously as a shrinkage reducer in therelatively smallest proportional parts. Polyethylene of differentmolecular weights can be used depending upon requirements.

The foaming agents obtained according to the invention are appropriatefor many uses, as packing material in building construction, inagriculture, where the foaming agents have an advantage in the workingenvironment, as covering foams, where due to its stability a thin layerof foam results in the desired sealing quality, as well as oilabsorption, particularly crude oil absorption and the like. They arebiologically degradable. Because they are almost completely porous,excellent oil absorption can be achieved within an extremely short time,which is of the highest advantage for oil spills of every kind.

The mixing and foaming of components A and B and the shaping and finalreduction of the foam can be achieved using conventional methods.Advantageous is the use of a device according to CH-PS 584.104.

    ______________________________________                                        Example 1:     Foaming agent hardener solution                                ______________________________________                                        970 parts by weight                                                                          Water                                                           18 parts by weight                                                                          Dodecylbenzolsulphonic acid                                     6 parts by weight                                                                           Phosphoric acid 85%                                             6 parts by weight                                                                           Polyethylene glycol                                             1,5 parts by weight                                                                         Resorcin                                                       ______________________________________                                    

are processed to a homogenous solution.

This solution is suitable for the manufacture of an aminoplasticcellular foam with a very stable foam structure by the addition of acommercial aminoplastic precondensate solution (BASF), for example, in afacility as described in the CH-PS 584.104. The biologically degradablefoam obtained in such a way is perfectly suitable for oil absorption, asa cover for dumping grounds and in agriculture.

EXAMPLE 2 Foaming Agent Hardener Solution

The quality constancy and the stability of the foam can be improvedfurther if the constituent 1.5 parts by weight named in example 1 aregiven a C₁₅ -C₂₂ -fatty alcohol that esterifies with one part of thedodecylbenzolsulphonic acid. Processed with known amino-resinprecondensates or a solution according to example 3 they are suitablefor building construction and provide high stability as well as beingshrinkage-free and odorless.

EXAMPLE 3 Resin Solution

80 to 82 parts by weight of a commercial 37 to 40% aminoplasticprecondensate solution (BASF) are mixed with 10 parts by weight sorbitoland 8 to 10 parts by weight 1,4-dibromide butene diol.

EXAMPLE 4 Aminoplastic Foaming Agent

In a facility according to CH-PS 584.104 the solutions obtained inexample 2 and example 3 were processed in a ratio of 1:2 to 1:3 to afireproof foam that displays the following characteristics.

Four different samples (100×100×100 mm) were taken after the foam (14 to18 kg/m³) had been dried. These samples were subjected to climatecontrol for 24 hours before the examination at 50 per cent by volumehumidity. Then they were therm-stabilized in an oven (3 hours at about80° C. over a steam bath). After these three hours the samples weretaken from the oven and dried for 24 hours in a climate controlled roomat 50 percent by volume humidity.

The mean weight loss of the four samples was 0,425 g per sample.

The mean linear mass loss per side of the cube was 1,58 mm.

An amino-resin foam of superior quality yields in practice under normal,physical conditions a linear shrinkage of at the most 0.2%. The moisturereleased during the drying phase contained on practical application onlytraces of formaldehyde, that are physiologically no longer perceptible.After subsequent drying the foam body remains stable and subsequentlydelivers no formaldehyde, as occurs with the more conventionally knownfoams.

I claim:
 1. A stable aminoplastic cellular foam comprising a reactionproduct of an amine formaldehyde precondensate constituent (A) with afoaming agent hardener constituent (B) wherein constituent (A) containsa halogenated alkene polyalcohol and/or constituent (B) containsdodecylbenzolsulphonic acid, optionally partially esterified with afatty alcohol, and contains a long-chain polyalcohol.
 2. Foam accordingto claim 1 wherein constituent (A) contains2,3-dibromide-2-butene-1,4-diol.
 3. Foam according to claim 1 whereinconstituent (B) contains one or more esters of dodecylbenzolsulphonicacid with C₁₅ -C₂₂ -fatty alcohol.
 4. Foam according to claim 2 whereinconstituent (B) contains one or more esters of dodecylbenzolsulphonicacid with C₁₅ -C₂₂ -fatty alcohol.
 5. Foam according to claim 1 whereinconstituent (B) contains polyethylene glycol.
 6. Foam according to claim2 wherein constituent (B) contains polyethylene glycol.
 7. Foamaccording to claim 3 wherein constituent (B) contains polyethyleneglycol.
 8. A process for manufacturing a stable aminoplastic cellularfoam comprising reacting an amine formaldehyde condensate constituent(A) with a foaming agent hardener constituent (B), wherein constituent(A) contains a halogenated alkene polyalcohol and/or constituent (B)contains dodecylbenzolsulphonic acid, optionally partially esterifiedwith a fatty alcohol, and contains a long-chain polyalcohol.
 9. Anaminoplastic precondensate constituent for manufacturing anemission-free, fireproof foam by conversion with a foaming agenthardener constituent, wherein the aminoplastic precondensate contains ahalogenated alkene polyalcohol.
 10. A precondensate constituentaccording to claim 9 containing 2,3-dibromide-2-butene-1,4-diol.
 11. Amethod of sound and/or heat insulating building construction comprisingfilling the construction with an emission-free, fireproof, lowshrinkage, stable aminoplastic cellular foam comprising a reactionproduct of an amine formaldehyde precondensate constituent containing ahalogenated alkene polyalcohol with a foaming agent hardenerconstituent.
 12. A method according to claim 11 comprising filling thebuilding construction with a foaming agent hardener constituentcontaining dodecylbenzolsulphonic acid, optionally partially esterifiedwith a fatty alcohol, and containing a long-chain polyalcohol.
 13. Amethod according to claim 12 comprising filling the buildingconstruction with a foaming agent hardener constituent containingdodecylbenzolsulphonic acid, optionally partially esterified with a C₁₅-C₂₂ -fatty alcohol.
 14. A method according to claim 13 comprisingfilling the building construction with a foaming agent hardenerconstituent containing polyethylene glycol.
 15. A method of absorbingoil comprising applying a stable aminoplastic cellular foam comprising areaction product of an amine formaldehyde precondensate constituent witha foaming agent hardener constituent containing dodecylbenzolsulphonicacid and a long-chain polyalcohol.
 16. A method of covering agriculturalor dumping grounds comprising applying stable aminoplastic cellularfoams comprising a reaction product of an amine formaldehydeprecondensate constituent with a foaming agent hardener constituentcontaining dodecylbenzolsulphonic acid and a long-chain polyalcohol.